The invention pertains generally to welding electrode tracking systems and more particularly to such systems that employ a substantially constant arc transfer current, either pulsed or sustained.
For many arc welding applications it is impractical to implement the welding torch support and drive mechanism such that the torch is always moved in a path exactly parallel to the weld joint centerline. In such cases it is necessary to use some type of weld joint tracking system. The tracking system senses the position of the welding torch or arc relative to the weld joint and uses this information in a feedback manner to reposition the torch relative to the weld joint as necessary to maintain the weld torch at a preselected orientation to the weld joint. Methods of sensing the torch position that have been previously used include: (1) visual inspection; (2) contacting electromechanical probes; and (3) non-contacting transducers. Each of these methods has met with varying degrees of success, depending primarily on the weld joint geometry and the arc visibility. Recent developments in narrow groove welding, however, have pointed to the need for sensing the position of the torch and arc relative to the narrow groove joint by a means that does not depend on any of the previously used methods. This uniqueness of the narrow groove welding requirement arises from its inherent poor arc visibility and extreme sensitivity to torch positioning.